Such securing and tensioning devices are required in order to enable a pipe that is to be introduced into a bore in the ground to be pulled behind a percussion boring machine that is forming the bore when it is not possible to join the pipe to the boring machine in a tension-proof manner. In a known securing and tensioning device of this kind one end of the towing cable is secured in a sleeve that is joined to the boring machine in a tension-proof manner and is passed through a towed pipe inserted into the sleeve. On the free end of the towed pipe is placed a thrust member having a displaceable device for clamping the cable. The clamping device comprises clamping jaws that can be tightened up by means of screws and are axially displaceable in a guide. Engaging with this guide there is a tensioning screw that is connected to the clamping jaws, by means of which the clamping jaws can be displaced axially.
This clamping and tensioning device is awkward to manipulate, since the clamping jaws must first be brought as close as possible to the thrust member by turning the tensioning screw, and the manually tensioned cable must then be clamped between the clamping jaws by tightening up the clamping screws, whereafter tensioning of the towing cable by turning the tensioning screw is possible. Furthermore, the length of the tensioning stroke is limited, so that it is not possible either to take account of the greater amount of stretching that occurs in the case of very long towed pipes or to re-tension if loosening occurs.